Apparatus for manufacturing synthetic jewels



Oct. 26, 1954 L. A. DAUNCEY 2,692,456

APPARATUS FOR MANUFACTURING SYNTHETIC JEWELS Filed July 8, 1952 2Sheets-Sheet 1 F F 7 8 E I l7 I7 30 2| l// 'Zl l I i 4 24 5 23 FIQI.

ITroRNeY Oct. 26, 1954 DAUNCEY 2,692,456

APPARATUS FOR MANUFACTURING SYNTHETIC JEWELS Filed July 8, 1952 2Sheefs-Sheet 2 F102. INVENTOR I Lso/wqRp qRz-m R qTTORNiFY Patented Oct.26, 1954 APPARATUS FOR MANUFACTURING SYNTHETIC JEWELS Leonard ArthurDauncey, London, England, assignor to The General Electric CompanyLimited, London, England Application July 8, 1952, Serial No. 297,707

Claims priority, application Great Britain July 13, 1951 2 Claims.

This invention is concerned with apparatus for manufacturing syntheticjewels.

It is known to manufacture synthetic jewels in the form of rods byprogressive crystallisation of molten material of which the jewels areconstituted. In apparatus which has hitherto been used to manufacturesynthetic jewels in this manner only a single rod has been produced at atime.

It is an object of the present invention to provide apparatus formanufacturing synthetic jewels in the manner described above in whichtwo or more rods may be produced simultaneously, thereby facilitating anincreased rate of production of synthetic jewels without incurring aproportional increase in the capital expenditure required.

According to the invention, apparatus for manufacturing synthetic jewelscomprises in combination means for passing through a primary duct astream of gas carrying the constituent material of the jewels in powderform, a distributor for splitting up the stream of gas issuing from theprimary duct so that it passes through at least two secondary ductsleading into a furnace chamber, the mean rates of flow of the gas andthe powder through the secondary ducts being substantially the same forall the secondary ducts, means for fusing the constituent materialissuing from the secondary ducts in the furnace chamber by a combustionprocess involving the gas issuing from the secondary ducts, a supportmember on which can be built up by progressive crystallisation of themolten constituent material a number (equal to the number of secondaryducts) of jewels in the form of rods which extend substantiallyvertically, and means for causing relative vertical movement between thesupport member and the openings of the secondary ducts into the furnacechamber as the rods are built up so as to maintain a substantiallyconstant distance between the tips of the rods and the openings of thesecondary ducts into the furnace chamber.

The distributor may comprise a first passage of annular cross-sectiondisposed around the primary duct and a second passage of annularcrosssection disposed around the first passage, the gas being arrangedto fiow from the primary duct through the first and second passagesrespectively to the secondary ducts so that the direction of flow of thegas is reversed as it passes from the primary duct to the first passageand as it passes from the first passage to the second passage.

One arrangement in accordance with the invention will now be described,by way of example, with reference to the accompanying drawings, inwhich:

Figure 1 is a diagrammatic view of apparatus for manufacturingsimultaneously six rods of synthetic corundum; and

Figure 2 is a sectional view of the distributor and the top of thefurnace chamber forming part of the apparatus shown in Figure 1.

Referring now to Figure l of the drawings, the raw material {or themanufacture is in the form of alumina powder and is disposed in acontainer l in a powder dispenser 2 mounted above a furnace chamberwhich is formed by a hollow glass cylinder 3 mounted between two metalplates 4 and 5. The container l is provided at the bottom with a finesieve 6 and a hammer mechanism 1 is provided for intermittently strikingthe container i so that powder is released. An oxygen supply isconnected via a pipe 8 to the interior of the dispenser 2 and the powderreleased from the container l is carried by the oxygen flow into aprimary duct extending downwards in the interior of a tubular member 9disposed between the dispenser 2 and the furnace chamber. The oxygen andalumina powder pass from the primary duct into a distributor, disposedinside the tubular member 9, which splits up the flow into six secondaryducts which lead into the top of the furnace chamber.

The distributor is shown in detail in Figure 2, to which referenceshould now' be made. The primar duct 10 extends axially through acylindrical member H which is mounted inside the tubular member 9. Thedistributor includes a first passage [2 of annular cross-sectionsurrounding the primary duct 10, and a second passage l3 of annularcross-section surrounding the first passage I2. The passage [2 is formedby two cylindrical surfaces, the inner one of which is formed on the endof the member H and the outer one of which is formed inside acylindrical member M which is supported by a cylindrical member I5mounted inside the tubular member 9. The passage I3 is formed by theouter surface of the member l4 and the inner surface of the member 9.The six secondary ducts l6 lead off from the end of the second passage[3, and it will be seen that the oxygen and alumina powder flow from theprimary duct [0 through the passages 12 and I3 respectively to thesecondary ducts IS, the direction of-flow being reversed as the oxygenand alumina powder pass from the primary duct In to the passage l2 andas they pass from the passage l2 to the passage [3.

The six secondary ducts [6 are arranged in radially symmetrical fashionand pass through the member l5, through tubes i1, and through acylindrical member l8 mounted on the top plate 4 of the furnace chamber,the secondary ducts l6 directing the flow of oxygen and alumina powdervertically downwards as they enter the furnace chamber. A separatehydrogen supply is connected to the furnace chamber via a pipe i9, thehydrogen being arranged to flow into the furnace chamber through atoroidal cavity 29 in the plate 4.

Combustion is caused to take place in the furnace chamber, six flames 2ibeing formed at the openings of the secondary ducts it into the chamber.The alumina powder issuing from the secondary ducts I6 is thus fused,and the molten material is arranged to be built up by progressivecrystallisation into six vertically extending rods 22 of syntheticcorundum. For this purpose there is provided a support member 23 whichincludes six ceramic rods 24 which extend vertically through an aperturein the base plate of the furnace chamber. The six rods 24 are arrangedin radially symmetrical fashion below the openings of the secondaryducts I6 into the furnace chamber, so that one of the six rods 22 ofsynthetic corundum is built up on the top of each of the six ceramicrods 24.

In order to ensure uniformity of the cross-section and quality of therods 22 of synthetic corundum it is necessary to move them verticallydownwards as they are built up so as to main-, tain a substantiallyconstant distance between the tips of the rods 22 and the openings ofthe secondary ducts l6 into the furnace chamber. For this purpose thesupport member 23 is mounted on a vertically extending rod 25 which isprovided with a rack of teeth 26 cooperating with a pinion wheel 21which is arranged to be driven by means of an electric motor 28. Themotor 28 is controlled by means of a photo-electric control apparatussuch as is described in British patent specification No. 633,118, thisapparatus including a photo-electric cell 29 on to which light from theincandescent tip of one of the rods 22 of synthetic corundum is fccussedby means of a lens 39. The output of the photoelectric cell 29 is fed toan amplifier and relay circuit 3! which controls the operation of themotor 28 in such a manner that the support member 23 is moved verticallydownwards at the required rate. It will be appreciated that thephoto-electric control apparatus is responsive to the growth of only oneof the rods 22, but the use of the distributor described above ensuresthat all the six rods 22 will be built up uniformly.

I claim:

1. Apparatus for manufacturing synthetic jewels, comprising membersdefining a furnace chamber, a primary duct, and at least two secondaryducts leading vertically into the furnace chamber, means for passingthrough the primary duct a stream of a first gas carrying theconstituent material of the jewels in powder form, a distributor forsplitting up the stream of gas issuing from the primary duct so that itpasses through the secondary ducts with the mean rates of flow of thegas and the powder through the secondary ducts being substantially thesame for all the secondary ducts, means for introducing into the furnacechamber a flow of a second gas adapted to undergo combustion with saidfirst gas to bring about fusion of the constituent material issuing fromthe secondary ducts into the furnace chamber, the openings of thesecondary ducts into the furnace chamber being spaced apart sufiicientlyto ensure that during combustion entirely separate flames are formed ateach of said openings, a support member on which can be built up byprogressive crystallisation of the molten constituent material a number(equal to the number of secondary ducts) of jewels in the form of rodswhich extend substantially vertically, and means for causing relativevertical movement between the support member and the openings of thesecondary ducts into the furnace chamber as the rods are built up so asto maintain a substantially constant distance between the tips of therods and the openings of the secondary ducts into the furnace chamber.

2. Apparatus according to claim 1, in which the distributor comprisesmembers defining a first passage of annular cross-section disposedaround the primary duct and a second passage of annular cross-sectiondisposed around the first passage and communicating with the secondaryducts, said members being shaped to guide the flow of gas from theprimary duct into the first passage with reversal of the direction offlow of the gas and to guide the flow of gas from the first passage intothe second passage with reversal of the direction of flow of the gas.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 365,606 Kline June 28, 1887 1,960,215 Ellis et al. May 22,1934 2,011,872 Rava Aug. 20, 1935 2,518,543 Hasse Aug. 15, 19502,591,561 Lester et al. Apr. 1, 1952 FOREIGN PATENTS Number Country Date633,118 Great Britain Dec. 12, 1949

